The present invention relates to a system for measuring and analyzing Cardio-Pulmonary-Resuscitation (CPR) parameters for use with and by an external defibrillator, including a training defibrillator.
The term external defibrillator covers all types of defibrillators that employ pads to be connected to the outside of the patient""s chest. This also includes training defibrillators, the appearance and behavior of which simulate a real defibrillator without being able to discharge defibrillator shocks. Training defibrillators are used with manikins during training and practice. As a comparison, an xe2x80x9cinternal defibrillatorxe2x80x9d or so-called implanted defibrillator is a device that is placed underneath the patient""s skin, and which has electrodes connected directly to the heart muscle.
For years, the use of defibrillators in the case of sudden cardiac death has been recognized as the only curative treatment. Defibrillation involves the discharge of an electric pulse with relatively high energy (defibrillator shock) through electrodes connected to the patient""s chest. Several designs of electrodes exist, but in the main they can be divided into two groups: xe2x80x9cPaddlesxe2x80x9d are electrodes that are held manually on the chest. Adhesive electrodes or xe2x80x9cPadsxe2x80x9d are electrodes that are attached to the chest by using an adhesive, and which make use of a conducting polymer in order to establish good electric contact with the skin.
External defibrillators use the electrodes to discharge the electrical shock, to measure the patient""s EGG, and to measure any impedance. The purpose of the impedance measurement is to determine the degree of electrical connection between the electrodes. If the impedance is close to zero, this would suggest a short circuit between the electrodes. In the opposite case, if the impedance is high, this would imply insufficient contact between the electrodes. Some types of defibrillators use impedance measurements in order to determine the voltage and time for discharging the defibrillator shock, so that the energy delivered to the patient is approximately equal to the desired energy.
Defibrillation may, by its very nature, involve a risk for those who treat the patient, if they touch the patient or in any other way come into contact with the electrodes. Therefore, the procedures for use include making sure everyone is clear before the shock is discharged. A defibrillator will employ voice messages in order to get the user and any assistants to follow procedures.
Traditionally, defibrillation has been carried out by highly trained personnel in hospitals. However, as automated defibrillators have developed over the last ten years and have become significantly easier to use, they have also come to be used outside of the hospitals, primarily by the ambulance services. There is also a clear tendency for defibrillators to be used by the laity before the ambulance reaches the patient. This refers especially to fire-fighters, police, guards and flight crews. Common to all of them is the fact that their profession is non-medical.
The trend today is that so-called patients at risk, for instance patients waiting for heart surgery, may have a defibrillator in their home, which can be operated by family members or others in the local environment in case of an emergency. Combined with giving the family CPR training, this ensures a high state of preparedness, in addition to an extra sense of security for the patient.
Unfortunately, attempts at resuscitation following sudden cardiac death are not always successful. When sudden cardiac death occurs, the outcome will among other things be dependent on all the links of the life-saving chain. These links are: Early notification of the support machinery, early CPR, early defibrillation and early advanced cardiac life support. The first treatment given to the patient is the most important. For the patient, it is of vital importance that the treatment not only be started as soon as possible, but also that the treatment is as effective and efficient as possible. In those cases where the heart does not start beating after the first three shocks given with a defibrillator, the treatment protocol prescribes one minute of CPR. The purpose of the CPR is to provide circulation of blood to the heart muscle, which increases the electrical activity in the heart, which in turn increases the probability of an electrical shock from a defibrillator being able to restart the heart. Thus, it is crucial for some patients that the CPR is administered effectively and correctly.
Operating an automated defibrillator is relatively simple, as today""s defibrillators employ voice messages to instruct the user, and the apparatus does not normally have more than two control buttons. Performing CPR correctly is however fairly difficult for those who are inexperienced, as this calls for a command of both method and psycho-motory skills. This despite the fact that the user has gone through training and practice.
It is becoming common practice, both in Norway and abroad, that a MECC (Medical Emergency Communication Center) instructs the user in first aid, including CPR, pending the arrival of the ambulance. This assumes that there is an accessible telephone by the patient, preferably with a speaker function so as to let the user concentrate on the patient without having to hold on to the telephone. However, a shortcoming of this situation is the fact that the MECC does not receive concise and quantitative feed-back regarding the events taking place, but have to interpret the situation as best they can based on the information received over the telephone.
Using a defibrillator and performing CPR on people generally presupposes that the user has gone through training and practice.
Today, all CPR training and practice includes the use of special manikins. These manikins have been constructed so as to allow inflations and chest compressions to be performed roughly in the same manner as on a lifeless person. Most manikins have been fitted with a number of sensors that among other things register lung inflations and chest compressions. This registration is used to provide visual feedback regarding the performance, as well as for generating a report on the performance with a view to certification in accordance with the guidelines. When defibrillator training is carried out, this may happen in two alternative ways: If the practice is non-interactive, the defibrillator or the training defibrillator will be equipped with simple adhesive electrodes that are attached to the manikin""s chest. Normally, there will be no interaction or communication between the manikin and the training defibrillator.
Interactive practice will normally entail the use of a real defibrillator and a manikin that for defibrillating purposes behaves as a human being. The general design for such interactive use has the manikin equipped with an internal load resistance connected to the connection points on the manikin""s chest. The patient cable from the defibrillator has been designed for connection to the connection points. The load resistance will indicate to the defibrillator that it is connected to a patient. Further, the manikin will be provided with a signal transmitter that simulates the electrical activity of the heart (ECG). The signal transmitter is connected to the load resistance, to ensure that this signal is also available to the defibrillator. Finally, the load resistance is designed in such a way as to enable it to absorb the defibrillator shocks. A sensor connected in series with the load resistance is normally designed to be able to influence the signal transmitter.
The object of the present invention is to provide a system that enables a person with limited knowledge and skills to perform CPR correctly, efficiently and more effectively, so as to give the patient better treatment and thereby a greater chance of survival.
It is also an object of the present invention to provide a system such that training and practice in the use of defibrillators of the type that measures and analyzes CPR parameters, with accompanying voice messages, may be as realistic as possible.
The information provided by the present invention is used by a defibrillator in order to give corrective voice messages to the user. In addition, this information may be transmitted to a medical emergency communication center (MECC) that will interpret the situation and guide the user during the resuscitation attempt. Moreover, the information collected will contribute towards documenting the treatment, which in turn is important with regards to quality assurance and treatment optimization.